In a processing system, certain devices have expected performance standards. These performance standards are satisfied by the retrieval of requested data from memory in a sufficient amount of time so as not to interrupt the operation of the requesting devices. Retrieval of data within the prescribed time can be accomplished by maintaining all of the data that the requesting devices may need to access in high performance, high speed memory with low latency for data accesses. This, however, can significantly increase the cost of the processing system because potentially a large amount of expensive high-speed memory would be needed.